Heat-sensitive recording material

Abstract

The invention relates to a heat-sensitive recording material, comprising a carrier substrate and at least one heat-sensitive thermal reaction layer, which is applied to at least one side of the carrier substrate and contains at least one fluoran color former, at least one color developer, at least one melting aid, and optionally typical additives, such as lubricants, stabilizers (anti-aging agents), and/or pigments, characterized in that the color developer is dodecyl gallate and the melting aid is an ethylene bis fatty acid amide of formula (I), wherein R1 and R2 are CH3(CH2)mCH2 with m=13 and/or 15. The invention further relates to a method for producing said recording material.

The invention claimed is: 
     
       1. A heat-sensitive recording material, comprising a carrier substrate and at least one heat-sensitive thermal reaction layer applied to at least one side of the carrier substrate, which layer contains at least one fluoran colour former, at least one colour developer, at least one melting aid and optionally a slip additive, a stabiliser, an anti-ageing agent, and/or a pigment, wherein the colour developer is dodecyl gallate and the melting aid is an ethylene-bis-fatty acid amide of Formula I, 
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are CH 3 (CH 2 ) m CH 2  with m=13 and/or 15, and wherein 1.5 to 4 parts by weight dodecyl gallate are used per 1 part by weight fluoran colour former;
 and wherein the melting aid has from 83.7 to 93.6 percent surface area of C 15 /C 18 , C 16 /C 16 , or C 18 /C 18  ethylene-bis-fatty acid amides and combinations thereof relative to the total of all ethylene-bis-fatty acid amides present and wherein the C 16 /C 18 , C 16 /C 16 , or C 18 /C 18  ethylene-bis-fatty acid amides are: 
 a) R 1 =CH 2 (CH 2 ) 13 CH 3 , (m=13) and R 2 =CH 2  (CH 2 ) 15 CH 3 , (m=15), (C 16 /C 18 -ethylene-bis-amide, ethylene-N-palmitamide-N1-steramide), 
 b) R 1 =R 2 =CH 2 (CH 2 ) 13 CH 3 , (m=13), (C 16 /C 16 -ethylene-Ns-amide, N,N1-ethylene-bis-palmitamide), and 
 c) R 1 =R 2 =CH 2 (CH 2 ) 15 CH 3 , (m=15), (C 18 /C 18 -ethylene-Ns-amide, N,N1-ethylene-bis-steramide), respectively. 
 
     
     
       2. A heat-sensitive recording material according to  claim 1 , wherein the at least one fluoran colour former is selected from the group 3-diethylamino-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-p-toluidinamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-(o,p-dimethylanilino)fluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-(cyclohexyl-N-methylamino)-6-methyl-7-anilinofluoran, 3-diethylamino-7-(m-trifluoromethylanilino)fluoran, 3-N-n-dibutylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-(m-methylanilino)fluoran, 3-N-n-dibutylamino-7-(o-chloroanilino)fluoran, 3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinofluoran, 3-(N-methyl-N-propylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-ethoxypropylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-isobutylamino)-6-methyl-7-anilinofluoran, and/or 3-dipentylamino-6-methyl-7-anilinofluoran. 
     
     
       3. A heat-sensitive recording material according to  claim 1 , wherein 0.5 to 5 parts by weight ethylene-bis-fatty acid amide of Formula I are used per 1 part by weight dodecyl gallate. 
     
     
       4. A heat-sensitive recording material according to  claim 1 , wherein the colour developer is present in an amount of from 3 to 35% by weight, relative to the total solids content of the heat-sensitive thermal reaction layer. 
     
     
       5. A heat-sensitive recording material according to  claim 1 , wherein the stabiliser is used in the form of sterically hindered phenols, 1,1,3-tris-(2-methyl-4-hydroxy-5-cyclohexylphenyl)-butane, 1,1,3-tris-(2-methyl-4-hydroxy-5-tert butylphenyl)-butane, 1,1-bis-(2-methyl-4-hydroxy-5-tert butyl-phenyl)-butane, urea-urethane compounds of the general formula III, 
       
         
           
           
               
               
           
         
       
       or oligomeric ethers of the general formula IV, 
       
         
           
           
               
               
           
         
       
       where n=1-3. 
     
     
       6. A heat-sensitive recording material according to  claim 1 , wherein precipitated calcium carbonate, aluminium hydroxide, kaolins, precipitated silicas or mixtures thereof are used as the pigment. 
     
     
       7. A heat-sensitive recording material according to  claim 1 , wherein paper, synthetic paper or plastics-material film, optionally with intermediate layers formed thereon, is used as the carrier substrate. 
     
     
       8. A heat-sensitive recording material according to  claim 1 , wherein the fluoran colour former comprises ODB-2. 
     
     
       9. A method for producing the heat-sensitive recording material of  claim 1  comprising applying an aqueous application suspension containing at least one fluoran color former, at least one color developer, and at least one melting aid to a carrier substrate using a curtain coating method, optionally with intermediate layers formed thereon, and drying, the aqueous application suspension having a solids content of approximately 20 to 75% by weight, containing as the colour developer dodecyl gallate and as the melting aid an ethylene-bis-fatty acid amide of Formula I, 
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are CH 3 (CH 2 ) m CH 2  with m=13 and/or 15, the aqueous application suspension being applied using the curtain coating method at an operating speed of at least approximately 400 m/min. 
     
     
       10. A method according to  claim 9 , wherein the curtain coating method is operated at a speed of at least approximately 1000 m/min. 
     
     
       11. A method according to  claim 9 , further comprising forming a layer on the thermal reaction layer online or offline as a protective layer and/or a layer which promotes printability. 
     
     
       12. A method according to  claim 9 , further comprising forming a layer on a side of the carrier substrate opposite the thermal reaction layer online or offline as a barrier layer and/or a layer which promotes printability. 
     
     
       13. A method according to  claim 10 , wherein the curtain coating method is operated at a speed of at least approximately 1500 m/min. 
     
     
       14. A heat-sensitive recording material, comprising a carrier substrate and at least one heat-sensitive thermal reaction layer applied to at least one side of the carrier substrate, which layer contains at least one fluoran colour former, at least one colour developer, at least one melting aid and optionally a slip additive, a stabiliser, an anti-ageing agent, and/or a pigment, wherein the colour developer is dodecyl gallate and the melting aid is an ethylene-bis-fatty acid amide of Formula I, 
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are CH 3 (CH 2 ) m CH 2  with m=13 and/or 15 and wherein the colour developer is present in an amount of from 3 to 35% by weight relative to the total solids content of the heat-sensitive thermal reaction layer, wherein 1.5 to 4 parts by weight dodecyl gallate are used per 1 part by weight fluoran colour former;
 and wherein the melting aid has from 83.7 to 93.6 percent surface area of C 16 /C 18 , C 16 /C 16 , or C 18 /C 18  ethylene-bis-fatty acid amides and combinations thereof relative to the total of all ethylene-bis-fatty acid amides present and wherein the C 16 /C 18 , C 16 /C 16 , or C 18 /C 18  ethylene-bis-fatty acid amides are: 
 a) R 1 =CH 2 (CH 2 ) 13 CH 3 , (m=13) and R 2 =CH 2  (CH 2 ) 15 CH 3 , (m=15), (C 16 /C 18 -ethylene-bis-amide, ethylene-N-palmitamide-N1-steramide), 
 b) R 1 =R 2 =CH 2 (CH 2 ) 13 CH 3 , (m=13), (C 16 /C 16 -ethylene-bis-amide, N,N1-ethylene-bis-palmitamide), and 
 c) R 1 =R 2 =CH 2 (CH 2 ) 15 CH 3 , (m=15), (C 18 /C 18 -ethylene-bis-amide, N,N1-ethylene-bis-steramide), respectively. 
 
     
     
       15. A heat-sensitive recording material according to  claim 14 , wherein 0.5 to 5 parts by weight ethylene-bis-fatty acid amide of Formula I are used per 1 part by weight dodecyl gallate. 
     
     
       16. A heat-sensitive recording material according to  claim 14 , wherein the stabiliser is used in the form of sterically hindered phenols, 1,1,3-tris-(2-methyl-4-hydroxy-5-cyclohexylphenyl)-butane, 1,1,3-tris-(2-methyl-4-hydroxy-5-tert butylphenyl)-butane, 1,1-bis-(2-methyl-4-hydroxy-5-tert butyl-phenyl)-butane, urea-urethane compounds of the general formula III, 
       
         
           
           
               
               
           
         
       
       or oligomeric ethers of the general formula IV, 
       
         
           
           
               
               
           
         
       
       where n=1-3. 
     
     
       17. A heat-sensitive recording material according to  claim 14 , wherein the fluoran colour former comprises ODB-2. 
     
     
       18. A heat-sensitive recording material according to  claim 14  comprising at least two ethylene-bis-stearic acid amides. 
     
     
       19. A heat-sensitive recording material according to  claim 14 , wherein a total EBS fraction is 88.5, 84.1, 85.5, 92.5, 91.2, 93.6, 83.7 or 89.1.